class FBO{
        constructor(gl){
            var framebuffer, texture, depthBuffer;

            //定义错误函数
            function error() {
                if(framebuffer) gl.deleteFramebuffer(framebuffer);
                if(texture) gl.deleteFramebuffer(texture);
                if(depthBuffer) gl.deleteFramebuffer(depthBuffer);
                return null;
            }
    
            //创建帧缓冲区对象
            framebuffer = gl.createFramebuffer();
            if(!framebuffer){
                console.log("无法创建帧缓冲区对象");
                return error();
            }
    
            //创建纹理对象并设置其尺寸和参数
            texture = gl.createTexture();
            if(!texture){
                console.log("无法创建纹理对象");
                return error();
            }
    
            gl.bindTexture(gl.TEXTURE_2D, texture);
            gl.texImage2D(gl.TEXTURE_2D, 0, gl.RGBA, resolution, resolution, 0, gl.RGBA, gl.UNSIGNED_BYTE, null);
            //gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.LINEAR);
            gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.NEAREST);
            gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.NEAREST);
            framebuffer.texture = texture;//将纹理对象存入framebuffer
    
            //创建渲染缓冲区对象并设置其尺寸和参数
            depthBuffer = gl.createRenderbuffer();
            if(!depthBuffer){
                console.log("无法创建渲染缓冲区对象");
                return error();
            }
    
            gl.bindRenderbuffer(gl.RENDERBUFFER, depthBuffer);
            gl.renderbufferStorage(gl.RENDERBUFFER, gl.DEPTH_COMPONENT16, resolution, resolution);
    
            //将纹理和渲染缓冲区对象关联到帧缓冲区对象上
            gl.bindFramebuffer(gl.FRAMEBUFFER, framebuffer);
            gl.framebufferTexture2D(gl.FRAMEBUFFER, gl.COLOR_ATTACHMENT0, gl.TEXTURE_2D, texture, 0);
            gl.framebufferRenderbuffer(gl.FRAMEBUFFER, gl.DEPTH_ATTACHMENT, gl.RENDERBUFFER,depthBuffer);
    
            //检查帧缓冲区对象是否被正确设置
            var e = gl.checkFramebufferStatus(gl.FRAMEBUFFER);
            if(gl.FRAMEBUFFER_COMPLETE !== e){
                console.log("渲染缓冲区设置错误"+e.toString());
                return error();
            }
    
            //取消当前的focus对象
            gl.bindFramebuffer(gl.FRAMEBUFFER, null);
            gl.bindTexture(gl.TEXTURE_2D, null);
            gl.bindRenderbuffer(gl.RENDERBUFFER, null);
    
            return framebuffer;
        }
    }